International Intercomparison of PV Modules Reaffirms Measurement Precision of the CalLab PV Modules
At 1.3 percent measurement precision, the accredited calibration laboratory of the Fraunhofer Institute for Solar Energy Systems ISE achieved a record value. Measurement repeatability is 0.4 percent. Germany’s national accreditation body DAkkS has confirmed this value according to DIN EN ISO/IEC 17025:2005. The excellent measurement precision of CalLab PV Modules was also proven in a recent comparison of PV module calibrations between the four best-known calibration laboratories worldwide. For PV power plant investors, the precise calibration of PV modules translates into more exact yield predictions and thus lower financial risks. PV manufactures require high measurement precision to ensure the highest-level quality assurance in production and the power measurements of their products.
For the international comparison, two standard and two high-efficiency silicon PV modules were measured by each of the four participating international reference laboratories. In addition to the CalLab PV Modules of Fraunhofer ISE in Freiburg, Germany that initiated and coordinated the comparison, three other laboratories were involved: the European Solar Test Installation (ESTI) of the European Commission’s Joint Research Centre (Ispra, Italy), the Research Center for Photovoltaics of the National Institute of Advanced Industrial Science and Technology (AIST; Tsukuba, Japan) and the National Renewable Energy Laboratory (NREL; Golden, CO, USA). Calibration measurements of the short-circuit current, the open-circuit voltage, the power at maximum power point and the fill factor were compared.
At the end of the exercise, all modules were sent back to CalLab PV Modules where they were re-measured. For the crystalline PV modules, the measured values showed deviations within a range of ±0.9 percent, whereas for the high-efficiency modules the deviations lay within only ± 0.2 percent in part. Even the maximum measured deviation of 0.9 % lay well below the value of the previous international comparison (2014: 1.3 percent). The JRC Ispra published the newest results in the October issue of “Solar Energy,” the official journal of the International Solar Energy Society®.